Extension-trestle.



No. 651,444. 4 Patented lune l2, I900. w. H. NELSON.

EXTENSION TRESTLE.

(Application filed Mar. 16, 1900.)

(No Model.)

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\VILLIAM H. NELSON, OF HAZLETON, IOlVA.

EXTENSlON-TRESTLE.

SPECIFICATION forming part Of Letters Patent NO. 651,444, dated J'une12, 1900.

' Application filed March 16, 1.900- Smi'fll 7- (N0 modem To all whom it may concern.-

Be it known that 1, WILLIAM H. NELSON, a citizen of the United States of America, and a resident of l-Iazleton, Buchanan county, and State of Iowa, have invented certain new and useful Improvements in Extension-Trestles, of which the following is a specification.

My invention relates to improvements in extension-trestles; and the object of my improvement is, first, to provide means whereby when workmen have once ascended the trestle they may elevate it to different heights without incurring the necessity of descending for that purpose, and, second, to provide other means for increasing the height of trestle when it has otherwise reached its capacity for extension. I attain these objects by the means which are illustrated in the accompanying drawings, in which-- Figure 1 is a side elevation of the trestle as partly extended, having a portion of the frame bars and legs removed in order to show the pulleys and cables. Fig. 2 is an end elevation of the trestle, showing it partly extended, but unprovided with the extension-legs; and Fig. 3 shows a leg of the trestle as seen from the end, having an extension-leg attached.

Similar letters refer to similar parts throughout the several views.

As is illustrated, or represents the upper or cross bar of an extension-trestle, supported at either end by the standards 79 and 7t.

b and b are frame-bars supported at points near their ends by the posts or legs n and n and r and r. The legs a and n and r and rare connected to the frame-bars b and b by means of bolts, as at a, which latter are furnished with nuts, as at z, for compressing the parts together.

In the longitudinal space between the framev bars I) and Z) are placed the pulleys s and w and rollers t and e, which move in bearings in the frame-bars. The lower part of the standard It is also provided with an opening extending fro m front to rear,in which is placed the pulley :20. Through the end of the crossbar a,outside the standard 70, a shaft 0 is passed perpendicularly and is retained vertically in position by being passed through an opening in the brace g, which latter is aflixed to the lower part of thestandard 7t. The shaft 0 is operated by means of a hand-lever cl at its vin the standard 7t.

top, and is retained in position by the ratchetwheel a and dog f.

The standards 7; and 7c move between the guides Z and Z and m and m, respectively, and the legs nand n are connected and braced by the beam 3 as are also the legs 1' and r by a similar beam.

To the shaft 0, at a point below the brace g,

is attached a cable h, which is arranged to wind about it, and thence around the pulleya: This cable after passing around this pulley is conducted upward and fastened to a bolt (not here shown) running across from the frame-bar b to the framebar 17.

If desired, the cable It may be attached to and wound about the shaft- 0 at any point above the brace 9 instead of below it.

u is a cable fastened at the point to to the forward under part of the cross-bar a. This cable is then passed under and about the pulley s and the roller 15, thence upward and about the roller oand pulley w, and thence downward to the lower part of the standard It, where it is fastened at the point 10 The extension-legs 0 0', &c., are, when it is thought necessary to add to the height of the trestle, connectedto the lower ends of the legs n n r r by means of the retaining-rings, such as are shownin Fig. 3 atp and (1. These rings are affixed to the extensions, and the lower rings have caps over the under part to form sockets for the reception of the legs of trestle.

The trestle is extended in'the following manner: The shaft 0 is rotated by means of the hand-bar d, the ratchet and dog keeping it in the position it assumed when released. The revolution of the shaft 0 causes the cable h to become wound about it, and the ca ble passing around the pulley a: elevates the standard 76 with the cross-bar a. In order to cause a simultaneous elevation of both standards 70 and k and to obviate cramping of the parts, the cablett is employed. As the crossbar a rises it draws with it the cable a from the point where itis attached at a. This cable, moving about the pulley s and roller t and the roller 1) and pulley w, draws upward the lower part of the standard It simultaneously with the elevation of the standard 70. It when the cross-bar a has been thus raised to any desired height it is thought best to keep it in that position for any certain time, the nuts on the bolts connecting the framebars I) and b are tightened up, as at 2, thus compressing the pulleyss and to between the bars and preventing their revolution. The cross-bar a maybe readily lowered on releasing the dog f from its engagement with the ratchet-wheel c. When the limit of extension of the trestle is reached, it may be increased in height by connecting to its legs the extensions 0 0, &c. This is done by slipping the upper rings of the extensions over the legs and then allowing the lower ends of the legs to settle into the sockets of the lower rings.

The trestle may be readily separated for packing by removing the bolts connecting the frame-bars.

It will be seen that by the use of the means illustrated it becomes unnecessary for a workman to descend and reaseend from his staging, but may elevate or depress it from the top while standing upon it.

Having described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is

1. In an extension-trestle, the combination of the cross-bar a, standards It and 70, framebars I) and b, pulleys m, s and w, rollers t and 1;, legs at, n, "rand 0', bolts a secured by nuts 2, slideways Z and Z, m and m, brace g, the shaft 0 provided with the ratchet-wheel e and dog and hand-lever d, with the cables h and u, all suitably connected and supported, substantially as shown and described.

2. In an extension-trestle, the combination of the cross-bar a, standards It and 70, framebars Z) and b, pulleys w, s and w, rollers t and 1:, legs a, n, r, 0', bolts 2 secured by nuts .2, slideways Z and Z, m and m, brace g, shaft 0 provided with ratchet-Wheel e and dog f and hand-bar (1, cables h and u, with the extension-legs 0, a, &c., provided with retainingrings 1') and g, &c., all suitably connected and supported, substantially as shown and described.

Signed by me at Ilazleton,l3uchanan county, Iowa, this 12th day March, 1900.

WILLIAM ll. NELSON.

\Vitnesses:

W. A. NELSON, TNES KIEFER. 

